Elastic Constants of Strontium Titanate (SrTi<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>)

Poindexter, Edward H.; Giardini, A. A.

doi:10.1103/physrev.110.1069

Cited by 47 publications

(14 citation statements)

References 4 publications

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“…The relevant anisotropic Poisson ratios ν ij can be obtained from the known elastic moduli of STO [21]. For samples whose edges are not aligned with the crystallographic axesê i the f ijkl above should be replced by f ′ ijkl = L ip L jq L kr L ls f pqrs with L ij =x i ·ê j and ν ij by the corresponding ν ′ ij .…”

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confidence: 99%

Strain-Gradient-Induced Polarization inSrTiO3Single Crystals

et al. 2007

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Piezoelectricity is inherent only in noncentrosymmetric materials, but a piezoelectric response can also be obtained in centrosymmetric crystals if subjected to inhomogeneous deformation. This phenomenon, known as flexoelectricity, can significantly affect the functional properties of insulators, particularly thin films of high permittivity materials. We have measured strain-gradient-induced polarization in single crystals of paraelectric SrTiO3 as a function of temperature and orientation down to and below the 105 K phase transition. Estimates were obtained for all the components of the flexoelectric tensor, and calculations based on these indicate that local polarization around defects in SrTiO3 may exceed the largest ferroelectric polarizations. A sign reversal of the flexoelectric response detected below the phase transition suggests that the ferroelastic domain walls of SrTiO3 may be polar.

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Strain-Gradient-Induced Polarization inSrTiO3Single Crystals

et al. 2007

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“…Based on single crystal elastic constants a Young's modulus E ͑along the cube axis͒ ranging from 265 to 303 GPa and a shear modulus G ranging from 119 to 127 GPa has been reported in four independent experiments. 25,30,31 Nanoindentation experiments gave a somewhat lower value for E : 225± 14 GPa. 32 For SrRuO 3 only a single reference was found pertaining to a polycrystalline sample giving E = 161 GPa and G = 60.1 GPa.…”

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Substrate influence on the shape of domains in epitaxial PbTiO3 thin films

Venkatesan

Kooi

Hosson

et al. 2007

Journal of Applied Physics

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Epitaxial PbTiO 3 thin films were grown on SrTiO 3 ͑001͒ and DyScO 3 ͑110͒ substrates by pulsed laser deposition. We used high-resolution transmission electron microscopy to investigate the 90°d omain structure in the films. They were found to have a predominant fraction of c domains along with a certain minor volume fraction of a domains that is clearly higher in case of the DyScO 3 substrates. In PbTiO 3 on SrTiO 3 the a domains were found to have a wedge shape, whereas in PbTiO 3 on SrRuO 3 / DyScO 3 they have a nearly uniform width. The presence of steps in the domain walls has been observed in the films on both substrates, but the steps are clearly more dominant in the case of SrTiO 3 than of SrRuO 3 / DyScO 3 and are responsible for the observed wedge shape. The observed difference in the films induced by the two substrates is attributed to a higher stiffness of SrTiO 3 than of SrRuO 3 / DyScO 3 as we corroborated with nanoindentation experiments.

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“…We found that the measured out-of-plane lattice constants deviate from those calculated assuming the volume conservation of RNiO3 unit cells. This Poisson's ratio in complex oxides is usually in the range of 0.2∼0.3 [38,39]. This is suggestive of a change in oxidation state under tensile strain, but not compressive strain.…”

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Strain-driven disproportionation at a correlated oxide metal-insulator transition

et al. 2020

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Metal-to-insulator phase transitions in complex oxide thin films are exciting phenomena which may be useful for device applications, but in many cases the physical mechanism responsible for the transition is not fully understood. Here we demonstrate that epitaxial strain generates local disproportionation of the NiO6 octahedra, driven through changes in the oxygen stoichiometry, and that this directly modifies the metal-to-insulator phase transition in epitaxial (001) NdNiO3 thin films. Theoretically, we predict that the Ni-O-Ni bond angle decreases, while octahedral tilt and local disproportionation of the NiO6 octahedra increases resulting in a small band gap in otherwise metallic system. This is driven by an increase in oxygen vacancy concentration in the rare-earth nickelates with increasing in-plane biaxial tensile strain. Experimentally, we find an increase in pseudocubic unit-cell volume and resistivity with increasing biaxial tensile strain, corroborating our theoretical predictions. With electron energy loss spectroscopy and xray absorption, we find a reduction of the Ni valence with increasing tensile strain. These results indicate that epitaxial strain modifies the oxygen stoichiometry of rare-earth perovskite thin films and through this mechanism affect the metal-to-insulator phase transition in these compounds. PACS numbers: 68.55.Ln, 68.60.Bs, 73.50.-h, 73.20.-r 3 Metal-to-insulator phase transitions (MITs) in strongly-correlated electronic systems are fascinating phenomena which have attracted significant attention for decades [1]. Among complex oxide materials which exhibit MITs are rare-earth nickelates having the generic formula RNiO3, where the rare-earth element (R) is smaller than lanthanum, i.e. R = Pr, Nd ... [2]. The critical temperature of the MIT is dependent on the Ni-O-Ni bond angle: straightening the angle with a larger R cation stabilizes the metallic state over the insulating state and lowers the transition temperature [3-5]. For example, the MIT temperatures in bulk NdNiO3 and SmNiO3 (Ni-O-Ni bond angles of 157.1 and 153.4°, respectively) have been reported to be approximately 200 and 400 K, respectively. It should be also emphasized that a breathing order by disproportionation of the Ni-O bond length plays a crucial role in the MIT [6-10].In RNiO3 thin films, misfit strain arising from a lattice mismatch between the film layer and the underlying substrate affects the lattice volume, electrical conductivity and MIT temperature [11][12][13][14][15][16][17][18]. In particular, films under in-plane tensile strain are more insulating compared to those under in-plane compressive strain. The origin of this interesting phenomenon remains unclear, although a number of mechanisms have been proposed [19][20][21][22][23][24].We also note that the effect of oxygen non-stoichiomety on the MIT has been reported in bulk RNiO3 [25,26].It is widely accepted that epitaxial strain in transition metal oxide films can be accommodated through the formation of oxygen vacancy defects, resulting in offstoi...

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Elastic Constants of Strontium Titanate (SrTiO3)

Cited by 47 publications

References 4 publications

Strain-Gradient-Induced Polarization inSrTiO3Single Crystals

Strain-Gradient-Induced Polarization inSrTiO3Single Crystals

Substrate influence on the shape of domains in epitaxial PbTiO3 thin films

Strain-driven disproportionation at a correlated oxide metal-insulator transition

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